LCQ9: Strengthening prevention and control of mosquito infestation
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Question:
Last year, there were multiple cases of chikungunya fever in Hong Kong, including imported cases and local cases. The Government earlier took interdepartmental actions, including conducting large-scale chemical mosquito control operations and eliminating potential mosquito breeding sites. Given that, based on historical data from the Food and Environmental Hygiene Department (FEHD), the gravidtrap indexes for Aedes albopictus are expected to rise significantly from April onwards, there are views that the Government should prepare for the prevention and control work early. In this connection, will the Government inform this Council:
(1) since the Government stepped up territory-wide mosquito control efforts in July last year, of the frequency and number of mosquito control operations conducted by the FEHD and relevant government departments in the 18 districts across the territory, and the rate of increase of the relevant figures compared with those in the same period last year (set out in a table);
(2) whether the Government will increase the frequency and number of mosquito control operations from April this year onwards to prevent mosquito infestation; if so, of the estimated rate of increase compared with the same period last year; and
(3) given that the Government earlier trialled new technologies such as new mosquito trapping devices, a robotic dog for mosquito control, large ultra-low volume foggers and drones to assist in mosquito control work, whether the Government has assessed the effectiveness of such technologies; if so, of the details?
Reply:
President,
Mosquito control is an important and ongoing task of the Government. Since Hong Kong recorded its first imported case of chikungunya fever (CF) in August last year, the Environment and Ecology Bureau (EEB) has convened several meetings of the interdepartmental Pest Control Steering Committee (PCSC) to review the enhanced mosquito prevention and control measures implemented by the Food and Environmental Hygiene Department (FEHD) and other departments. With the rainy season approaching and the anticipated increase in the risk of mosquito-borne diseases, the EEB convened another PCSC meeting in March this year to provide steer to the continued strengthening of mosquito prevention and control work through a multi-pronged approach.
Regarding the question from the Hon Joephy Chan, our reply is as follows:
(1) Details of the enhanced mosquito prevention and control measures implemented by the FEHD and relevant departments since July 2025 are as follows:
Vector surveillance
The FEHD continues to place gravidtraps in different areas across Hong Kong for monitoring the infestation of Aedes albopictus mosquitoes and publishes the Area Gravidtrap Indices (AGI) on a regular basis, so that government departments and stakeholders can adopt targeted mosquito control measures with respect to the surveillance results. To further step up mosquito prevention and control, since August last year, the FEHD has extended its strengthened mosquito control work, which was originally initiated when the AGI of an area has reached 20 per cent (Level 3), to also cover areas with AGI between 10 per cent and 20 per cent (Level 2), until further notice. The FEHD will conduct detailed risk assessment for the areas concerned and carry out intensive and targeted mosquito control work jointly with other departments and stakeholders. The FEHD will also notify property management companies and residents of the nearby housing estates to stay vigilant and join hands in taking anti-mosquito measures.
Minimising mosquito breeding grounds and eliminating mosquitoes
With the primary focus on environmental control, the FEHD's mosquito prevention and control work focuses on minimising mosquito breeding grounds. Biological or chemical methods are also applied to control mosquito populations. Measures include applying larvicides to drains and gully traps; conducting fogging operations at adult mosquito resting sites to eliminate adult mosquitoes; clearing water-holding containers, clearing blocked drains, and levelling depressions to eliminate stagnant water.
During the period from July to December in the past two years (2024 and 2025), the number of mosquito breeding sites eliminated and the number of fogging operations conducted to eliminate adult mosquitoes by FEHD, with a breakdown by District Council districts, are set out in Annexes I and II. In the second half of 2025, the number of mosquito breeding sites eliminated and fogging operations conducted increased by approximately 11 per cent and 36 per cent respectively compared with the same period in 2024.
Inter-departmental and cross-sectoral collaboration
The FEHD has convened meetings of the inter-departmental task forces on anti-mosquito work across districts to coordinate with relevant departments and stakeholders in implementing targeted and sustained mosquito prevention and control measures.
The FEHD also called on the property management sector and the pest control sector to implement anti-mosquito measures among the work units or residents of the housing estates under their management. Moreover, the FEHD, the Property Management Services Authority and the Centre for Health Protection of the Department of Health jointly held a large-scale seminar providing information on the prevention and control measures against CF for practitioners of the property management sector.
The FEHD has also collaborated with the Development Bureau to issue the "Guidelines on Mosquito Prevention in Construction Sites" to construction sites and relevant personnel through the Construction Industry Council, reminding the practitioners to strengthen mosquito prevention and personal protection. In addition, prior to the start of the new school year last year, the FEHD issued the "Guidelines on Mosquito Prevention in Schools" through the Education Bureau to over 2 000 schools across the territory, including kindergartens, primary schools and secondary schools, to assist schools in preventing mosquito-borne diseases.
(2) The gravidtrap index for Aedes albopictus for the first two months of this year has remained low, consistent with the same period in past years. As spring approaches, the gravidtrap index is anticipated to rise along with warmer weather and the rainy season as in previous years. Under the PCSC's supervision, departments will remain vigilant, closely monitor the gravidtrap index across districts, conduct risk assessments, and strengthen mosquito prevention and control measures at locations with relatively higher infestation levels. The FEHD will continue to convene meetings of the inter-departmental task forces on anti-mosquito work in the district to co-ordinate active actions by relevant departments and stakeholders, including eliminating potential mosquito breeding places before the rainy season, conduct on-site inspections, and provide relevant departments with professional advice and technical guidance.
Given that departments adjust their action plans based on risk assessments and other factors in addition to routine mosquito prevention and control work, we are unable to estimate at this stage the number or frequency of mosquito control operations to be conducted this year.
(3) The FEHD has been actively applying technology to enhance the effectiveness of mosquito control work. The effect of the technology mentioned in the question are as follows:
New mosquito trapping devices
The FEHD has introduced new mosquito trapping devices, which can simultaneously suppress larval growth and eliminate adult mosquitoes, into its routine mosquito control operations. As these traps have proven effective in mosquito control, the FEHD has placed more than 2 000 new mosquito trapping devices in various districts across the territory, and recommended that other government departments adopt the devices at venues under their management. In addition, the FEHD, in collaboration with the Education Bureau, will progressively install the new mosquito trapping devices in registered secondary schools, primary schools and special schools to strengthen mosquito control on campuses.
Mosquito control robot dogs
The FEHD, in collaboration with the Electrical and Mechanical Services Department, has studied the installation of ultra‑low volume (ULV) sprayers on remotely operated robot dogs. This replaces the need for pest control workers to carry ULV sprayers, enabling fogging operations to be conducted in hard‑to‑reach areas such as woodlands and densely vegetated sites, thereby enhancing the effectiveness of mosquito control. Field trials of a robot dog commenced in September last year, and in December it assisted in fogging operations along the Tsing Yi Nature Trail with satisfactory results. The FEHD is introducing two more robot dogs to support mosquito control work across districts.
Large mechanical ultra-low volume fogger
The FEHD has introduced large ULV fogger mounted on robotics vehicles. These vehicles are remotely controlled by operators to conduct fogging operations at target locations to eliminate adult mosquitoes. The mechanical vehicles typically operate on relatively flat and wide roads, with a wider fogging range, facilitating large-scale fogging operations, thereby enhancing the efficiency of mosquito control work.
Drones
The FEHD has deployed high‑precision professional surveying drones to capture images in hilly areas with complex terrain and dense vegetation. Through high‑resolution photographs, stagnant water and concealed mosquito breeding sites can be accurately identified, enabling the formulation of targeted mosquito control measures. Drones can cover extensive areas within a short period of time, significantly reducing inspection time and manpower requirements. They also replace the need for frontline staff to physically enter high‑risk or hard‑to‑reach locations, thereby enhancing overall operational effectiveness.
The FEHD will closely monitor the latest information from the World Health Organization and other places concerning mosquito control measures. The FEHD will also study the feasibility of introducing the new technologies and products to Hong Kong, conduct field trials at appropriate times to assess their effectiveness, and actively introduce and apply suitable new technologies and products.
Ends/Wednesday, April 1, 2026
Issued at HKT 11:55
Issued at HKT 11:55
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